#include<iostream>
#include<vector>
using namespace std;

class Solution {
public:
    int mySqrt(int x)
    {

        if (x < 1)return 0;
        long long  left = 0, right = x;
        while (left < right)
        {
            long long mid = left + (right - left + 1) / 2;
            if (mid * mid <= x)left = mid;
            else right = mid - 1;
        }
        return left;

    }
};
int main()
{
    int x = 0;
    int ret=Solution().mySqrt(x);
	return 0;
}